Encontrados 11 documentos, a visualizar página 1 de 2
Integrated synthesis of nanosized semiconductors in a bioremediation system for...
Costa, J. P. da; Girão, Ana Violeta; Lourenço, J. P.; Monteiro, O. C.; Trindade, Tito; Costa, Maria ClaraThe use of sulfate-reducing bacteria in bioremediation process for the treatment of afluents with high-content of sulfate and metal generates an excess of sulfide.
Use of biogenic sulfide for the synthesis of CuS nanocrystals and nanocomposites
Pinto da Costa, João; Girão, Ana Violeta; Lourenço, J. P.; Monteiro, O. C.; Trindade, Tito; Costa, Maria ClaraDuring the metabolism of organic matter (CH2O), sulfate-reducing bacteria (SRB) use sulfate as the terminal electron acceptor, resulting in the production of H2S. This biologically generated sulfide, in the presence of metal ions, can be used for metal precipitation (Bhagat et al., 2004). The use of SRB in bioremediation processes, namely, in the reduction of highcontent sulfate and metal effluents, is well doc...
HDPE/mesoporous silica nanocomposites by in-situ polymerisation: structural det...
Bento, A.; Lourenço, J. P.; Fernandes, A.; Pérez, E.; Cerrada, María L.; Ribeiro, M. R.Mesoporous silicas exhibit stable three-dimensional structures, made of ordered channels with well-defined geometries and dimensions at nanometer scale, able to host intercalation reactions.
Cycloaddition reactions of nitrosoalkenes, azoalkenes and nitrile oxides mediat...
Lemos, A.; Lourenço, J. P.Mg:Al 3:1 hydrotalcite (Ht), used in catalytic quantities, promotes the generation of nitrosoalkenes, azoalkenes and nitrile oxides. These can be intercepted in situ by heterocycles and olefins in [4+2] and [3+2] cycloaddition reactions, producing dihydro-1,2-oxazines, tetrahydropyridazines and isoxazolines. The regeneration and reuse of Ht without loss of activity and the absence of organic solvent are the mai...
MCM-41 as Nanofiller in Polyethylene Hybrid Materials
Ribeiro, M. R.; Campos, João M.; Bento, A.; Lourenço, J. P.; Pérez, E.; Cerrada, María L.Mesoporous MCM-41 exhibits a stable framework structure, well-defined nanopores and a large surface area. When combined with metallocene polymerisation catalyst, these mesoporous materials, provide a unique route for preparing polyolefin-based nanocomposites by in situ polymerisation.
Al-containing MCM-41 type materials prepared by different synthesis methods: hy...
Lourenço, J. P.; Fernandes, A.; Henriques, C.; Ribeiro, M. F.Al-containing MCM-41 type materials were prepared by three different synthesis methods (aluminum grafting on the calcined MCM-41, pH adjustment during the crystallization period and crystallization in the presence of zeolite seeds). The samples were characterized by powder XRD, nitrogen adsorption, 27Al MAS NMR and FTIR with pyridine as probe molecule. All the samples exhibit a high hydrothermal stability at hi...
Evidence of a solvent screen effect affecting the redox properties of Co(II) io...
Gabelica, Z.; Louati, A.; Borges, C.; Ribeiro, M. F.; Lourenço, J. P.; Murphy, D. M.Cyclic voltammetric experiments of framework Co(II) ions in three different CoAPO structures have provided evidence for a screening effect created by solvent or template molecules which results in a facile oxidation (and a difficult reduction) of the Co(II) ions incorporated into the most open (the less strained) structures. An apparent contradiction of these findings with respect to theoretical expectations is...
Efficient co-templating roles of amines and amides admixed with alkylammonium s...
Borges, C.; Ribeiro, M. F.; Henriques, C.; Duarte, M.; Lourenço, J. P.; Gabelica, Z.Two different aluminophosphate structures were synthesised in aqueous media using as main template methylamine (MA), directly added, or generated in situ from methylformamide (MF). Both involve novel AlPO4-n topologies that undergo structural transformations upon template removal, yielding above 350°C microporous thermostable materials with interesting properties. Tetraalkylammonium (TEA) cations were used opti...
Disproportionation of ethylbenzene over SAPO-40
Lourenço, J. P.; Ribeiro, M. F.; Ramôa Ribeiro, F.; Rocha, J.; Gabelica, Z.SAPO-40 exhibits strong acid sites, which catalyse the reaction of disproportionation of ethylbenzene. The distribution of diethylbenzene isomers suggests a high void volume in the structure of this molecular sieve.
Síntese e caracterização de silicoaluminofosfatos do tipo SAPO-40
Lourenço, J. P.; Ribeiro, M. F.; Ribeiro, F. R.; Rocha, J.; Gabelica, Z.Os aluminofosfatos e silicoaluminofosfatos constituem duas das novas famílias de sólidos microporosos com estrutura tipo zeolítico. Estes materiais que apresentam elevada estabilidade térmica e hidrotérmica,podem possuir propriedades ácidas importantes, que associadas à sua estrutura de poros, lhes conferem novas e interessantes potencialidades de utilização no domínio da catálise, adsorção e permuta iónica.
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